AbstractLatin American and South European countries share a common policy legacy of public Pay-As-You-Go (PAYG) pension systems, yet reform paths taken over the past decades between and within the two regions have varied. Latin American countries opted for the full or partial privatization of their public pension systems, yet subsequent reforms have challenged the public–private mix. Meanwhile, countries in Southern Europe opted for a less radical path, entailing different degrees of reform of their public pillars and the introduction of supplementary private ones. Our analysis focuses on Argentina, Chile, and Uruguay – in Latin America – and Spain, Italy, and Greece – in Southern Europe – and the reforms implemented since 1990. In understanding reform variation, we argue that by focusing on the role of political institutions and policy legacies, it is possible to identify reform mechanisms.